This invention relates to a device for automatically stopping and restarting an engine.
Tokkai 2000-274273 published by the Japanese Patent Office in 2000 discloses a vehicle engine automatic stop/restart device wherein the engine of a vehicle can restart without torque shock due to a gear change-over by preventing the change-over of an automatic transmission.
In this device, when the engine automatically stops with the automatic transmission in a drive range, a restart is performed in the drive range. Hence, a creep force is generated immediately after restart, and a torque shock due to E a gear change-over does not occur.
However, in a vehicle equipped with an automatic stop/restart device of this type, the engine is restarted based on the command of a control unit irrespective of the intention of the driver, for example, to charge the battery.
If the brake pedal depression force is weakened while the driver remains unaware of it when the engine has automatically stopped, the vehicle will gradually move off when the engine is restarted, for example, to charge the battery, and an uncomfortable feeling is given to the driver.
It is therefore an object of this invention to suppress a creep force small and to prevent a vehicle moving off when an engine restarts unintended by a driver.
In order to achieve above object, this invention provides an engine automatic stop/restart device for an engine of a vehicle, the vehicle having a drive wheel, and a transmission mechanism which transmits a creep force to the drive wheels according to the rotation of an engine.
The automatic stop/restart device comprises a motor for starting the engine, a sensor which detects if the transmission mechanism is in a drive range wherein the creep force is transmitted to the drive wheel, a sensor which detects that a brake pedal is depressed, and a microprocessor.
The microprocessor is programmed to stop the running of the engine automatically when the vehicle is stationary with the brake pedal depressed, determine whether a driver or a vehicle state requires a restart of the engine, restart the engine to increase the rotation speed of the engine rapidly by the motor when the driver requires the restart of the engine, and restart the engine to increase the rotation speed of the engine more slowly by the motor when the vehicle state requires the restart of the engine with the transmission mechanism in the drive range.